package drds.server.config.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Set;

/**
 * 
 */
public class OrderRetainingMap<K, V> extends HashMap<K, V> {
	private static final long serialVersionUID = 1L;

	private Set<K> keyOrder = new ArraySet<K>();
	private List<V> valueOrder = new ArrayList<V>();

	@Override
	public V put(K key, V value) {
		keyOrder.add(key);
		valueOrder.add(value);
		return super.put(key, value);
	}

	@Override
	public Collection<V> values() {
		return Collections.unmodifiableList(valueOrder);
	}

	@Override
	public Set<K> keySet() {
		return Collections.unmodifiableSet(keyOrder);
	}

	@Override
	public Set<java.util.Map.Entry<K, V>> entrySet() {
		throw new UnsupportedOperationException();
	}

	private static class ArraySet<T> extends ArrayList<T> implements Set<T> {

		private static final long serialVersionUID = 1L;
	}

}